It is frequently necessary to install an underground pipe between two given points such as the opposed sides of a finished street or driveway, for example. It is routine procedure to provide an operating trench on one side and a target trench on the opposed side, and an installer device is properly positioned in the operating trench.
A first rod length is manually inserted through drive jaw means of the installer device and engaged thereby to push said first rod length toward the target trench, generally by a fluid operated cylinder and piston assembly. The trailing end of the first rod length is provided with a coupling to receive a second rod length and the drive means is activated to push the second rod length forwardly toward the target trench. A sufficient plurality of rod lengths are similarly attached to preceding lengths and driven forwardly until the leading tip end of the first rod length emerges into the target trench.
The leading trip end is threadedly provided with a pusher cap which is removed and replaced with an adapter for attachment to an end of a pipe to be permanently installed under the above surface. For this purpose, the direction of movement is reversed to pull the rods with the pipe attached thereto back through the hole, formed by the rod, until the leading end of the pipe emerges into the operating trench.
The above described operations are quite conventional, however, it is essential to stabilize the installer device during the rod pushing operation. It is particularly essential to stabilize the rear end of the device to keep the rod on a true course through the soil. Normally, the penetration of the pipe into the soil will stabilize the front end if the rear end is stabilized, and, stabilizing the rear end prevents a twisting or pivotal movement of the installer device which would permit the rod to deviate from its intended path of penetration.
Therefore, one of the principal objects of the present invention is to provide a pair of adjustable, vertically disposed abutment members on opposed sides of the rear end of the underground pipe installer device, to maintain the device in a properly centered aligned disposition within the operating trench during the rod pushing operation.
A further object of the invention is to provide a compound scissors linkage between the rear end of the installer device and the respective abutments with the linkage being operably connected to a vertical screw shaft, having an extended upper end, shaped and configurated for reception in the socket of an elongated wrench for manipulation of the abutments from a position outside of the operating trench.